Cleans up Jenkins EC2 slaves which have failed to launch. Use this script as a system groovy script with Groovy Plugin.

gistfile1.groovy

import jenkins.model.Jenkins
import hudson.slaves.OfflineCause

for (node in Jenkins.instance.getNodes()) {
    computer = node.toComputer()
    if (computer.getOfflineCause() instanceof OfflineCause.LaunchFailed) {
        node.terminate()
    }
}